A Study on GPS/GLONASS Compact Network RTK and Analysis on Temporal Variations of Carrier Phase Corrections for Reducing Broadcast Bandwidth

Junesol Song, Byungwoon Park, Changdon Kee

Peer Reviewed

Abstract:	Network Real-Time Kinematic (RTK) is capable of achieving cm-level positioning accuracy as conventional single-baseline RTK. Furthermore, it greatly reduces the required number of reference stations for precise positioning service to cover the same area, compared to single-baseline RTK, by utilizing observations from multiple reference stations. Consequently, Network RTK is considered as a candidate solution for navigation of land vehicles to realize Intelligent Transportation System (ITS). The major challenges in applying such augmentation of Global Navigation Satellite System (GNSS) to land vehicles include the possible low visibility problem according to the surrounding environment and the communication delay or failure. The lack of visibility prohibits users to obtain positioning results. In addition, the latency error in Network RTK corrections, associated with communication problems, introduces the loss of the fixed integer ambiguity and it eventually degrades the positioning accuracy of the land vehicles. Such failures in precise navigation can threat the safety of the land vehicles for the ITS. In this paper, GPS/GLONASS Network RTK is developed and combined with Compact RTK not only to increase visibility, but also to compensate the latency errors caused by communication delays. Compact RTK is a technique of generating correction for extremely low rate data-link, which is developed by Seoul National University. Currently, the protocol of Compact RTK is assigned in the RTCM SC-104 proprietary message, MT 4081 for GPS signals. In order to apply Compact RTK for GLONASS signals as well, the variations of GPS and GLONASS Carrier Phase Corrections (CPC) are analyzed. For various latency tests, the performance of ambiguity resolution is assessed in the aspects of success rate and time-to-fix for a static user. Moreover, the performance of the developed GPS/GLONASS Compact Network RTK is validated and it is compared with one of the commercial Network RTK services, Virtual Reference Station (VRS), which is provided by National Geographic Information Institute (NGII) of South Korea. In addition, the developed system is tested for various speeds of the data-link. As a result, GPS/GLONASS Compact Network RTK can be established with 1200 bps data-link with only 1 mm degradation in 3D Root-Mean-Square (RMS) positioning accuracy and maintaining 100% success rate for ambiguity resolution at the same time.
Published in:	Proceedings of the ION 2017 Pacific PNT Meeting May 1 - 4, 2017 Marriott Waikiki Beach Resort & Spa Honolulu, Hawaii
Pages:	659 - 669
Cite this article:	Song, Junesol, Park, Byungwoon, Kee, Changdon, "A Study on GPS/GLONASS Compact Network RTK and Analysis on Temporal Variations of Carrier Phase Corrections for Reducing Broadcast Bandwidth," Proceedings of the ION 2017 Pacific PNT Meeting, Honolulu, Hawaii, May 2017, pp. 659-669. https://doi.org/10.33012/2017.15099
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